Community Music Tools

I’ve started playing a little bit with AudioScrobbler and Goombah. I think the idea of gathering (and predicting/guessing at) useful bits of information from large amounts of data is pretty cool. I like Goombah because it will mine existing data rather than just harvest it in real time. Also, AudioScrobbler still hasn’t shown me any musical neighbors and it’s been over a week since I started giving them data… perhaps I’m very unique in my musical tastes?

What other community music tools have you used? What kind of experience have you had?